With the evolution of photoelectricity and semiconductor technologies, the vigorous development of a Flat Panel Display has been driven, while a Liquid Crystal Display (LCD) has become the market mainstream due to lots of advantageous properties, such as high utilization efficiency of space, low power consumption, no radiation and low electromagnetic interference, etc., among many flat panel displays. A LCD generally includes a Liquid Crystal Panel and a Back Light Module (BL). Since the LCD is a passive display which does not possess a self-luminescent function, a backlight module hereby needs to be installed to provide a display light source required by the display panel. As such, whether a surface light source generated by the backlight module possesses enough and uniform luminance directly affects the display quality of the LCD. Also, a LED becomes a first choice of the application light source of the backlight module due to the characteristics such as high light emitting efficiency, long life and low power consumption, etc.
Currently, the backlight module may be classified into two types, an Edge Lighting and a Direct Lighting, according to the structure thereof. An edge lighting backlight has advantages such as low power consumption and thin thickness, etc., but weight is heavy and cost is relatively high due to use of a light guide plate. In a liquid crystal display with a supersize (more than 100 inches), since the size of the panel is large, the transmittance thereof is low and the requirement for color gamut is high. Since the size is relatively large, many optical parts, such as a light guide plate, either cannot be produced with an appropriate size, or can be produced with an appropriate size by paying huge price. Hence, a direct lighting type backlight is generally adopted in a liquid crystal display with a supersize, although the direct lighting type backlight uses less number of light sources, has no light guide plate and has low cost, it is disadvantageous to thinning a product due to a light box being positioned high and thick appearance.